CVE-2025-8023 in Mattermost
Summary
by MITRE • 08/21/2025
Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.9.x <= 10.9.2 fails to sanitize path traversal sequences in template file destination paths, which allows a system admin to perform path traversal attacks via malicious path components, potentially enabling malicious file placement outside intended directories.
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Analysis
by VulDB Data Team • 08/21/2025
CVE-2025-8023 represents a critical path traversal vulnerability affecting multiple versions of the Mattermost collaborative platform. This vulnerability stems from inadequate sanitization of template file destination paths within the application's file handling mechanisms. The flaw exists in versions 10.8.x through 10.8.3, 10.5.x through 10.5.8, 9.11.x through 9.11.17, and 10.9.x through 10.9.2, indicating a widespread issue across the software's release history. The vulnerability specifically targets the template file processing functionality where user-supplied or administrative input is not properly validated before being used as part of file path construction.
The technical implementation of this vulnerability allows a system administrator with sufficient privileges to manipulate file paths through malicious path components that bypass normal sanitization checks. When the application processes template files, it incorporates user-provided path elements directly into the destination file paths without proper validation or encoding. This creates an opportunity for attackers to craft path traversal sequences such as ../ or ..\ that can navigate outside the intended directory structure. The vulnerability operates at the file system level where the application's template engine fails to properly canonicalize or validate the constructed file paths, enabling attackers to write files to arbitrary locations on the server's file system.
From an operational impact perspective, this vulnerability presents a severe risk to organizations relying on Mattermost for collaboration and communication. An attacker who can escalate to system administrator privileges could potentially place malicious files in critical system directories, execute arbitrary code, or overwrite important application files. The attack vector specifically targets administrative functions where path traversal sequences are accepted as legitimate input, making it particularly dangerous in environments where administrators have elevated privileges. The vulnerability could enable attackers to establish persistence mechanisms, escalate privileges, or disrupt normal application functionality through file corruption or replacement attacks.
The security implications extend beyond simple file placement, as this vulnerability aligns with CWE-22 Path Traversal and follows patterns consistent with ATT&CK technique T1059 Command and Scripting Interpreter. Organizations should implement immediate mitigations including updating to patched versions of Mattermost, implementing strict input validation for all file path operations, and monitoring for unauthorized file system modifications. Additionally, organizations should enforce principle of least privilege for administrative accounts, implement file system access controls, and conduct regular security audits of file handling operations within the application. The vulnerability demonstrates the importance of proper input validation and sanitization in preventing path traversal attacks, particularly in applications that handle user-supplied template or file path data. Security teams should also consider implementing file system integrity monitoring solutions to detect unauthorized file modifications that could result from exploitation of this vulnerability.